Effect of microplasma treatment on stratum corneum lipid molecule

The stratum corneum is a lipid matrix with embedded corneocytes. This layer protects the body against foreign substances and the outer environment. However, the lipid matrix is permeable to selective molecules and this permeability can be improved by several methods. One of these methods includes microplasma irradiation of the skin. Stearic acid is a model fatty acid from the lipid matrix of stratum corneum. In this study, the interaction between microplasma and stearic acid was investigated. Plasma was generated at a low voltage of about 800 V (0-Vpeak) using a thin dielectric (∼30 m) as a barrier. The plasma electrode treated the lipids under an argon atmosphere at a frequency of 25 kHz. The results of the microplasma treatment were investigated by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) and X-ray photoelectron spectroscopy. The concentrations of C, O and N atoms were determined before and after the microplasma treatment. Also, functional groups of C-C/C-H, C-O, C=O, OH-C=O, N-C=O were identified in the carbon spectra. The structure of stearic acid was evaluated by analysis of CH2, CH3 and C=O bands in the ATR-FTIR spectrum.